Internal gear pumps are known. They have an annulus and a pinion, which is arranged eccentrically in the annulus and meshes with the annulus in a segment of the circumference. The annuluses are internally toothed gearwheels, while the pinions are externally toothed gearwheels, and the annulus and the pinion can also be taken to be gearwheels of the internal gear pumps. The designations pinion and annulus are used to distinguish them. Opposite the segment of the circumference in which the gearwheels mesh there is a crescent-shaped free space between the annulus and the pinion, and this is referred to here as the pump space. Arranged in the pump space is a divider, on which tooth tips of the two gearwheels rest externally and internally and which divides the pump space into a suction space and a pressure space. Owing to its typical shape, the divider is often also referred to as a crescent or crescent piece. Another name for the divider is filler piece. When driven in rotation, the gearwheels deliver fluid from the suction space into the pressure space. Internal gear pumps without a divider are also known, and these are referred to as toothed ring pumps for the sake of distinguishing them.
German Patent DE 196 13 833 B4 discloses an internal gear pump of this kind having its own housing, by means of which it can be flanged to an electric motor used to drive it, for example. This internal gear pump is not provided for hydraulic vehicle brake systems.
German Laid-Open Application DE 10 2009 047 626 A1 discloses an internal gear pump for a hydraulic vehicle brake system which does not have its own housing but is installed in a hydraulic block of a slip control system of a hydraulic vehicle brake system. The hydraulic block can be taken to be a housing of the internal gear pump.
Such hydraulic blocks are known and they are used for the mechanical fixing and hydraulic interconnection of hydraulic components of a slip control system. Among such components are not only internal gear pumps but also solenoid valves and hydraulic accumulators for the slip control system. The hydraulic block is usually a cuboidal part made of metal, especially aluminum, in which countersunk holes, typically cylindrical and often with a stepped diameter, as sockets for the hydraulic components of the slip control system, and drilled holes, which hydraulically interconnect the sockets and the components installed therein, are made.